An adverse consequence of the nuclear age is the potential proliferation and distribution of materials that can be hazardous or even catastrophic in their misuse. The United States Nuclear Regulatory Commission classifies special nuclear material into three broad categories based upon potential threat. Category 1 includes strategic special nuclear material; category 2 includes special nuclear material of moderate strategic significance; and category 3 includes special nuclear material of low strategic significance. Each of the three categories of special nuclear material can be configured into a potential threat, ranging from a thermonuclear or atomic warhead to a clandestine nuclear weapon to a so-called dirty bomb.
Unfortunately, special nuclear material can become a significant risk in quantities on the order of kilograms. The ease of portability of such potentially devastating materials makes detection and monitoring of special nuclear material of paramount concern to citizens and governments worldwide. Conventional radiation detectors can be used to locate radioactive materials, but conventional radiation detectors typically detect the mere presence of a radioactive source. Accordingly, there is a need for an improved system for detecting special nuclear material that is readily deployable, easy to distribute, and highly accurate and reliable.